Investigation of the pathophysiology of fecal seepage

BACKGROUND AND AIM:   Unintentional seepage of stool without awareness is common but its pathophysiology is poorly understood. Our aim was to examine the underlying mechanism(s) for fecal seepage.
METHODS:   We evaluated prospectively 25 patients with fecal seepage, by performing anorectal manometry, balloon expulsion, saline infusion, pudendal nerve latency tests, and symptom assessments and compared their data with 26 fecal incontinence patients and 43 healthy controls.
RESULTS:   Predisposing factors for fecal seepage were back injury (7), obstetric injury (6), hemorrhoidectomy (3), pelvic radiotherapy (1), and unknown (8). In the seepage group, the resting and squeeze sphincter pressures were lower ( p < 0.02) than healthy controls, but higher ( p < 0.002) than incontinent group. During straining, the intrarectal pressure and defecation index were lower ( p < 0.05) in the seepage group compared to controls; 72% showed dyssynergia and balloon expulsion time was prolonged ( p < 0.01). Threshold for first rectal sensation was impaired ( p < 0.002) in the seepage group compared to controls and incontinent group. The seepage group retained more ( p < 0.001) saline than the incontinent group but pudendal nerve latency time was impaired ( p < 0.05) in both patient groups compared to controls.
CONCLUSIONS:   Anal sphincter function and rectal reservoir capacity were relatively well preserved but most patients with seepage demonstrated dyssynergia with impaired rectal sensation and impaired balloon expulsion. Thus, incomplete evacuation of stool may play a significant role in the pathogenesis of seepage.     

Anorectal dysfunction in patients with urologic disturbance due to multiple sclerosis

Anorectal function was evaluated in 11 patients with voiding dysfunction due to multiple sclerosis. In six patients with constipation, three also had symptoms of obstructed defecation and one patient was incontinent due to stercoral diarrhea. One patient was only fecal incontinent and one patient had obstructed defecation as the only symptom. Three patients had no anorectal symptoms. Anal manometry in the women compared with a control group revealed significant lower anal resting and squeeze pressures, although no significant difference of rectal sensation to distention with air was found. Pudendal nerve terminal latencies were obtained in seven patients and were all normal. In four patients latency could not be demonstrated due to poor contraction of the sphincter on stimulation of the pudendal nerve. Two of these patients were incontinent and two had both constipation and obstructed defecation. It is concluded that patients with voiding symptoms due to multiple sclerosis often reveal anorectal symptoms or motility disorders. Although anal sphincter function is reduced, fecal incontinence is not prevalent in this group. The reason for this lies probably in the fact that many of the patients are constipated, thus securing fecal continence.     

Absence of effect of nicotine on rectal sensation,rectal compliance,and anal sphincter pressures in healthy subjects

We examined the effect of nicotine on rectal sensation, rectal compliance, and anorectal sphincter function in healthy volunteers. Eleven healthy (ex-smoker) subjects were randomized in a double-blind, crossover, placebo-controlled study of 12 mg nicotine-containing chewing gum. All treatment periods (nicotine or placebo chewing gum) were preceded by a control period without chewing gum. Crossover study was done after a washout period of more than seven days. The following measurements were made: highest anorectal sphincter tone, highest anorectal sphincter squeeze tone, percentage relaxation of the anorectal sphincter with rectal ballon distension, threshold of rectal sensation, maximal tolerable volume of air inflation of a rectal balloon, and rectal compliance. There was no significant difference in the two control periods. Chewing placebo gum had no significant effect on any of the measurements when compared with control. Compared with placebo, nicotine did not significantly affect on any of the measurements. We conclude that neither nicotine nor the sham-feeding effect of chewing placebo gum appear to have any effect on anorectal sensorimotor function or on rectal compliance in healthy ex-smokers.Supported by a grant from the Park Ridge Health Foundation, Park Ridge, Illinois. Nicorette chewing gum and placebo chewing gum were kindly supplied by Marion Merrill Dow Inc., Kansas City, Missouri.     

便秘型和腹泻型肠易激综合征患者肛门直肠运动及直肠感觉功能的检测分析

目的研究便秘型和腹泻型肠易激综合征(IBS)患者肛门直肠运动及直肠感觉改变。方法对2000-01~2004-01广州医学院第二附属医院根据罗马Ⅱ标准入选的便秘型IBS30例,腹泻型IBS20例,正常对照组26例,进行肛门直肠运动功能及直肠感觉测定。结果(1)便秘型和腹泻型IBS肛门括约肌压力、肛门括约肌最大缩窄压和正常对照组相比差异无显著性(P>0.05);增加腹压时,肛门括约肌净增压腹泻型低于正常对照组(P<0.05);模拟大便时直肠和肛门括约肌出现同步收缩发生率便秘型IBS高于正常对照组(P<0.01)。(2)便秘型IBS直肠对容量刺激的最低敏感量、最大耐受性、顺应性明显高于正常对照组(P<0.01)。(3)腹泻型IBS直肠对容量刺激的最低敏感量、最大耐受性、顺应性明显低于正常对照组(P<0.01)。结论(1)IBS存在肛门直肠运动异常。(2)便秘型IBS直肠对容量刺激低敏感、高耐受、高顺应性,可能是引起便秘原因之一。(3)腹泻型IBS直肠对容量刺激存在高敏感、低耐受、低顺应性和肛门自控能力减弱,可能与腹泻有关。     

Anorectal manometry in patients with chronic constipation: a single-center experience

BACKGROUND/AIMS: Constipation is a common complaint, but its clinical presentation varies with each individual. The aim of this study was to evaluate anorectal physiology in a prospective group of patients with chronic constipation. METHODOLOGY: A total of 24 consecutive patients with constipation underwent solid-state anorectal manometry. Fifteen healthy controls were also studied. The anorectal parameters included resting and squeeze sphincter pressure, sensory thresholds in response to balloon distension, compliance of rectum, and rectoanal inhibitory reflex (RAIR). RESULTS: The rectal sensitivity for urge and pain did not differ between the groups, but the threshold volume for first sensation was higher in patients with constipation (p < 0.05). There was no group difference in the volume threshold for RAIR. However, the prevalence of impaired RAIR was higher in constipated patients. Anal pressure was lower in patients for maximal squeeze (p < 0.05). There was a positive correlation between the anal sphincter length and resting pressure in patients (r = 0.51, p = 0.03) and healthy controls (r = 0.72, p = 0.01). CONCLUSIONS: Constipated patients are characterized by impaired rectal sensitivity and decreased anal sphincter contractile pressure. Anorectal manometry is helpful for diagnosing anorectal dysfunction in patients with chronic constipation.     

Transanal endoscopic microsurgery excision: is anorectal function compromised?

PURPOSE: Transanal endoscopic microsurgery is a new technique that has not yet found its place in routine practice. The procedure results in dilation of the anal sphincter with a large-diameter operating sigmoidoscope, sometimes for a prolonged period. The purpose of the present study was to assess the effect of transanal endoscopic microsurgery on anorectal function. METHODS: Eighteen consecutive patients undergoing transanal endoscopic microsurgery excision of rectal tumors, of whom 13 were available for evaluation, were included. Continence was scored by a numeric scale before surgery and at three and six weeks after surgery. Anorectal physiology studies were performed preoperatively and six weeks postoperatively with manometry, pudendal nerve motor terminal latency, anal mucosal electrosensitivity, rectal balloon volume studies, and endoanal ultrasound. RESULTS: There was a significant reduction in mean anal resting pressure (104 ± 32 cm H2O before surgery, 73 ± 30 cm H2O after surgery; P = 0.0009). There was no significant change in squeeze or cough pressure, pudendal nerve terminal motor latency, anal mucosal electrosensitivity, or rectal balloon study volumes. Fall in resting pressure was significantly correlated with length of operating time (r2 =0.39, P = 0.047). There was no significant change in mean continence score after surgery. CONCLUSION: Transanal endoscopic microsurgery results in a reduction in internal sphincter tone. This did not affect continence in a short-term study.     

Phenotypic variation in functional disorders of defecation

BACKGROUND & AIMS: Although obstructed defecation is generally attributed to pelvic floor dyssynergia, clinical observations suggest a wider spectrum of anorectal disturbances. Our aim was to characterize phenotypic variability in constipated patients by anorectal assessments. METHODS: Anal pressures, rectal balloon expulsion, rectal sensation, and pelvic floor structure (by endoanal magnetic resonance imaging) and motion (by dynamic magnetic resonance imaging) were assessed in 52 constipated women and 41 age-matched asymptomatic women. Phenotypes were characterized in patients by principal components analysis of these measurements. RESULTS: Among patients, 16 had a hypertensive anal sphincter, 41 had an abnormal rectal balloon expulsion test, and 20 had abnormal rectal sensation. Forty-nine patients (94%) had abnormal pelvic floor motion during evacuation and/or squeeze. After correcting for age and body mass index, 3 principal components explained 71% of variance between patients. These factors were weighted most strongly by perineal descent during evacuation (factor 1), anorectal location at rest (factor 2), and anal resting pressure (factor 3). Factors 1 and 3 discriminated between controls and patients. Compared with patients with normal (n = 23) or reduced (n = 18) perineal descent, patients with increased (n = 11) descent were more likely (P < or = .01) to be obese, have an anal resting pressure >90 mm Hg, and have a normal rectal balloon expulsion test result. CONCLUSIONS: These observations demonstrate that functional defecation disorders comprise a heterogeneous entity that can be subcharacterized by perineal descent during defecation, perineal location at rest, and anal resting pressure. Further studies are needed to ascertain if the phenotypes reflect differences in the natural history of these disorders.     

The relationship of pudendal nerve terminal motor latency to squeeze pressure in patients with idiopathic fecal incontinence

PURPOSE: With the advent of transanal ultrasonography it has been possible to identify those incontinent patients without sphincter defects. The majority of these patients are now thought to have neurogenic fecal incontinence secondary to pudendal neuropathy. They have been found to have reduced anal sphincter pressures and increased pudendal nerve terminal motor latencies. The aim of this study was to determine whether in those incontinent patients who do not have a sphincter defect, prolonged pudendal nerve terminal motor latency correlates with anal manometry, in particular maximum squeeze pressure. METHODS: Sixty-six incontinent patients were studied with transanal ultrasonography, anorectal manometry, and pudendal nerve terminal motor latency. Twenty-seven continent controls had anorectal manometry and pudendal nerve terminal motor latency measured. RESULTS: Maximum resting pressure and maximum squeeze pressure were significantly lower in the group of incontinent patients with bilateral prolonged pudendal nerve terminal motor latency (median maximum resting pressure = 26.5 mmHg; median maximum squeeze pressure = 60 mmHg) when compared with incontinent patients with normal bilateral pudendal nerve terminal motor latencies (median maximum resting pressure = 46 mmHg; median maximum squeeze pressure = 79 mmHg; maximum resting pressure P = 0.004; and maximum squeeze pressure P = 0.04). In incontinent patients with no sphincter defects no correlation between pudendal nerve terminal motor latency and maximum squeeze pressure was found (r = -0.109, P = 0.48) and maximum squeeze pressure did not correlate with bilateral or unilateral prolonged pudendal nerve terminal motor latency (r = -0.148, P = 0.56 and r = 0.355, P = 0.19 respectively). CONCLUSIONS: In patients with idiopathic fecal incontinence damage to the pelvic floor is more complex than damage to the pudendal nerve alone. Although increased pudendal nerve terminal motor latency may indicate that neuropathy is present, in patients with neuropathic fecal incontinence, pudendal nerve terminal motor latency does not correlate with maximum squeeze pressure. Normal pudendal nerve terminal motor latency does not exclude weakness of the pelvic floor.     

Anal incontinence in patients with Addison's disease: a gluco- and mineralocorticoid independent sphincter malfunction?]

Anorectal motor function was evaluated in 15 female patients with Addison's disease and androgen deficiency and 15 age-matched healthy volunteers. Medical history revealed symptoms of faecal incontinence in 5 patients. The patients showed decreased maximum retention volumes (p less than 0.01) in the rectal saline infusion test. Lowered anal sphincter resting (p less than 0.01) and squeeze pressure (p less than 0.01) was demonstrated in patients with adrenocortical insufficiency. No differences between patients and controls were found in respect of perception volume, minimal distension volume for sphincter relaxation and rectal compliance by means of intrarectal balloon distension. Electromyography of the external anal sphincter was performed in 8 patients and showed no evidence for a neurogenic defect. Relevant morphological changes of the anorectum could be excluded endoscopically in 13 of the 15 patients. Therefore impaired anorectal muscular function is responsible for faecal incontinence in patients with Addison's disease and androgen deficiency. Further investigations will show, whether these findings are the consequence of lowered androgen production.     

肠易激综合征患者肛门直肠感觉阈值和动力学的改变

采用PC Polygraf HR高分辨多道胃肠功能测定仪,检测42例肠易激综合征(IBS)患者的肛门直肠压力、直肠容量感知、疼痛阈值、耐受阈值等指标,并与15例健康人做对照.结果发现IBS的直肠静息压、肛管括约肌静息压、最大缩窄压及肛管长度与对照组无显著性差异(P＞0.05),而初始感觉阈值、疼痛阈值、排便阈值腹泻组低于正常对照组(P＜0.05),便秘组高于正常对照组(P＜0.05).排便时IBS便秘组患者的肛管松弛压高于正常对照组(P＜0.05).提示IBS患者排便功能和直肠感觉功能存在异常.     

Pelvic floor neuropathy: a comparative study of diabetes mellitus and idiopathic faecal incontinence.

Twenty one patients with diabetic peripheral neuropathy, 18 with idiopathic faecal incontinence and 11 normal controls were studied with techniques of mucosal electrosensitivity, rectal distension for the quantitative assessment of anorectal sensation, and manometric and electromyographic tests for the assessment of anorectal motor function. An asymptomatic sensorimotor deficit was found in the anal canal of patients with diabetic peripheral neuropathy. Mucosal electrosensitivity thresholds in the anal canal were significantly higher (p less than 0.01 v controls) and fibre density of the external anal sphincter significantly raised (p less than 0.0001 v controls). Anal manometry and pudendal nerve terminal motor latencies were similar to controls. In patients with idiopathic faecal incontinence the tests of sensory and motor function also showed a sensorimotor neuropathy; compared with controls, mucosal electrosensitivity thresholds were significantly higher (p less than 0.002), anal canal resting and maximum squeeze pressures were significantly lower (p less than 0.05 and p less than 0.002 respectively), and pudendal nerve terminal motor latencies and fibre density of the external anal sphincter were significantly raised (both p less than 0.05). Sensory thresholds to rectal distension were similar in all groups. Pelvic floor sensorimotor neuropathy in diabetic patients has several features in common with that of patients with idiopathic faecal incontinence but its functional significance remains uncertain.     

The appreciation of rectal distention in fecal incontinence

The subjective response to rectal balloon sensation was assessed with anorectal manometry and pudendal nerve terminal motor latency measurement (PNTML) in three groups of patients. There were 37 healthy subjects, 54 patients with idiopathic fecal incontinence (IFI), and 36 with complete rectal prolapse and incontinence (CRP). There was no significant difference for any parameter of rectal balloon sensation between patients with IFI and normals. Patients with CRP differed only in onset (P=.001). The results show that the appreciation of rectal distention is maintained in IFI.     

Clinical and manometric effects of combined external beam irradiation and brachytherapy for anal cancer

This study evaluates anorectal function after combined tele- and brachytherapy for anal cancer using manometric measurements and a standardized questionnaire. Eight patients received 44±3 Gy external beam radiation followed by 20±4 Gy interstitial brachytherapy with iridium-192. Patients were examined 43 months (range 25–83) after therapy. Maximum anal basal pressure, squeeze pressure, and squeeze increment were significantly lower in patients (50, 163, 115 mmHg, respectively) than in control subjects (75, 285, 180 mmHg, respectively). Decreased anal elasticity was not observed. Anal prestretch “normalized” the contractility of the internal and external sphincter. Thus damage to the anal epithelium and hemorrhoidal cushions seems to be the most important mechanism explaining reduced anal closing pressure values. The rectoanal inhibitory reflex was observed in all but one patient. Rectal compliance was significantly reduced. Whereas all patients could retain a water filled rectal balloon until the maximum tolerable sensation level was reached, the rectal saline infusion test was strongly abnormal. Four patients were perfectly continent. Four patients were incontinent for gas and presented urgency in case of liquid stools with limited soiling occurring once weekly or less; three of them also had urgency for solids. Defecation frequency was increased but regular in most patients. Reduced anal closure together with reduced rectal compliance are at the basis of stool frequency, urgency and partial incontinence with occasional soiling. However, enough reserve sphincter function was maintained to preserve a clinically acceptable degree of anal continence in our patients. Accepted: 21 November 1997     

Functional activity of the rectum： A conduit organ or a storage organ or both？

AIM: To investigate whether the degree of rectal distension could define the rectum functions as a conduit or reservoir. METHODS: Response of the rectal and anal pressure to 2 types of rectal balloon distension, rapid voluminous and slow gradual distention, was recorded in 21 healthy volunteers (12 men, 9 women, age 41.7±10.6 years). The test was repeated with sphincteric squeeze on urgent sensation. RESULTS: Rapid voluminous rectal distension resulted in a significant rectal pressure increase (P < 0.001), an anal pressure decline (P < 0.05) and balloon expulsion. The subjects felt urgent sensation but did not feel the 1st rectal sensation. On urgent sensation, anal squeeze caused a significant rectal pressure decrease (P < 0.001) and urgency disappearance. Slow incremental rectal filling drew a rectometrogram with a "tone" limb representing a gradual rectal pressure increase during rectal filling, and an "evacuation limb" representing a sharp pressure increase during balloon expulsion. The curve recorded both the 1st rectal sensation and the urgent sensation. CONCLUSION: The rectum has apparently two functions: transportation (conduit) and storage, both depending on the degree of rectal filling. If the fecal material received by the rectum is small, it is stored in the rectum until a big volume is reached that can affect a degree of rectal distension sufficient to initiate the defecation reflex. Large volume rectal distension evokes directly the rectoanal inhibitory reflex with a resulting defecation.     

Relationship between symptoms and disordered continence mechanisms in women with idiopathic faecal incontinence

BACKGROUND AND AIMS: Anal sphincter weakness and rectal sensory disturbances contribute to faecal incontinence (FI). Our aims were to investigate the relationship between symptoms, risk factors, and disordered anorectal and pelvic floor functions in FI. METHODS: In 52 women with "idiopathic" FI and 21 age matched asymptomatic women, we assessed symptoms by standardised questionnaire, anal pressures by manometry, anal sphincter appearance by endoanal ultrasound and magnetic resonance imaging (MRI), pelvic floor motion by dynamic MRI, and rectal compliance and sensation by a barostat. RESULTS: The prevalence of anal sphincter injury (by imaging), reduced anal resting pressure (35% of FI), and reduced squeeze pressures (73% of FI) was higher in FI compared with controls. Puborectalis atrophy (by MRI) was associated (p<0.05) with FI and with impaired anorectal motion during pelvic floor contraction. Volume and pressure thresholds for the desire to defecate were lower, indicating rectal hypersensitivity, in FI. The rectal volume at maximum tolerated pressure (that is, rectal capacity) was reduced in 25% of FI; this volume was associated with the symptom of urge FI (p<0.01) and rectal hypersensitivity (p = 0.02). A combination of predictors (age, body mass index, symptoms, obstetric history, and anal sphincter appearance) explained a substantial proportion of the interindividual variation in anal squeeze pressure (45%) and rectal capacity (35%). CONCLUSIONS: Idiopathic FI in women is a multifactorial disorder resulting from one or more of the following: a disordered pelvic barrier (anal sphincters and puborectalis), or rectal capacity or sensation.     

Anorectal manometric abnormalities and effect of cisapride in patients with chronic idiopathic constipation

OBJECTIVES : To investigate abnormalities in anorectal motility, changes in rectal visceral perception of balloon distention and the effect of cisapride on patients with chronic idiopathic constipation (CIC). METHODS : Anorectal manometry was carried out in 30 CIC patients using the Synectics Visceral Stimulator combined with PcPolygraf before and after treatment with cisapride (10 mg three times daily for 4 weeks). Twenty age‐matched controls were also studied before cisapride therapy. RESULTS : Patients with CIC had lower anorectal sphincter squeeze pressures (P < 0.05), larger minimum relaxation volumes necessary to elicit the anorectal inhibitory reflux (P < 0.05), higher rectal defecation volume thresholds and higher rectal maximum tolerable volume thresholds (P < 0.01) compared with the controls. All of the abnormalities significantly improved and defecation frequency greatly increased after 4 weeks of cisapride therapy (P < 0.01). Cisapride was effective in 46.67% of patients with CIC. CONCLUSIONS : Patients with CIC have abnormalities of both anorectal motility and rectal visceral perception of balloon distention. Cisapride can improve these abnormalities and is effective in approximately one‐half of CIC cases.     

Effects of acute hyperglycaemia on anorectal motor and sensory function in diabetes mellitus.

AIMS: To determine the effects of acute hyperglycaemia on anorectal motor and sensory function in patients with diabetes mellitus. METHODS: In eight patients with Type 1, and 10 patients with Type 2 diabetes anorectal motility and sensation were evaluated on separate days while the blood glucose concentration was stabilized at either 5 mmol/l or 12 mmol/l using a glucose clamp technique. Eight healthy subjects were studied under euglycaemic conditions. Anorectal motor and sensory function was evaluated using a sleeve/sidehole catheter, incorporating a barostat bag. RESULTS: In diabetic subjects hyperglycaemia was associated with reductions in maximal (P<0.05) and plateau (P<0.05) anal squeeze pressures and the rectal pressure/volume relationship (compliance) during barostat distension (P<0.01). Hyperglycaemia had no effect on the perception of rectal distension. Apart from a reduction in rectal compliance (P<0.01) and a trend (P=0.06) for an increased number of spontaneous anal sphincter relaxations, there were no differences between the patients studied during euglycaemia when compared with healthy subjects. CONCLUSIONS: In patients with diabetes, acute hyperglycaemia inhibits external anal sphincter function and decreases rectal compliance, potentially increasing the risk of faecal incontinence.     

Abnormal visceral autonomic innervation in neurogenic faecal incontinence.

Changes of denervation in the anal sphincter striated and smooth muscle in patients with neurogenic faecal incontinence are well established. This study aimed to determine if there is also a more proximal visceral autonomic abnormality. Thirty women with purely neurogenic faecal incontinence (prolonged pudendal nerve latencies and an intact sphincter ring) and 12 patients with neuropathic changes together with an anatomical disruption were studied. Two control groups consisted of 18 healthy volunteer women and 17 women with normal innervation but an anatomically disrupted sphincter. Rectal sensation was assessed using balloon distension and electrical mucosal stimulation, and anal sensation by electrical stimulation. Rectal compliance was studied to determine whether sensory changes were primary or caused by altered rectal wall viscoelastic properties. Anal canal pressure changes in response to both rectal distension and rectal electrical stimulation were measured to assess the intrinsic innervation of the internal anal sphincter. Patients with neurogenic incontinence alone had impaired rectal sensation to distension (53.1 v 31.5 ml, p < 0.05, neurogenic v controls) and to electrical stimulation (24.4 v 14.8 mA, p < 0.005). Patients with neurogenic incontinence and sphincter disruption also showed impaired sensation compared with healthy controls (55.8 ml v 31.5 ml, p < 0.05 and 22.9 mA v 14.8 mA, p < 0.05). Patients with only a disrupted sphincter had normal visceral sensation to both types of testing. Both rectal compliance and the response of the internal anal sphincter to rectal distension and electrical stimulation were normal in all patient groups. This study suggests that there is a visceral sensory abnormality in patients with neurogenic incontinence which is not caused by altered rectal compliance. As evaluated in this study the intrinsic innervation of the internal anal sphincter is not affected in this process.     

Role of anorectal sensation in preserving continence.

The role of anal sensation in preserving continence was studied in nine healthy volunteers. Objective assessment of sphincter function by manometry and rectal saline infusion was carried out during topical anaesthesia of the anal canal using 5% lignocaine gel and during lubrication with the same amount of inert gel. Anaesthesia successfully abolished anal sensation and reduced both the amplitude and duration of the voluntary squeeze. Basal pressure was unaffected, but the rectal volume required to produce a sustained internal sphincter relaxation was increased. Saline continence was not impaired. Indeed, two subjects, who were previously unable to retain the full 1500 ml of rectally infused saline, did so when the anal canal was anaesthetised. Our findings suggest that anal sensation is not a critical factor in preserving continence. This implies that the incontinence experienced after anorectal surgery or neuropathy cannot be explained by lack of anal sensation alone.     

Strength-Duration Testing of the External Anal Sphincter in Females with Anorectal Dysfunction

PURPOSE: The strength-duration test has been suggested as a means of assessing external anal sphincter function. This study was designed to investigate this claim by comparing the strength-duration test with established measures of external anal sphincter function. METHODS: Forty-nine females undergoing diagnostic anorectal testing (manometry, rectal sensation, electromyogram, pudendal nerve terminal motor latency, and endoanal ultrasound) also had the strength-duration test performed (which was repeated for each patient after a short rest period). RESULTS: The strength-duration test was repeatable. Statistically significant correlations were found between this test at pulse durations of 3 ms, 1 ms, and 0.3 ms with electromyographic activity of the external anal sphincter and with pressure in the anal canal during voluntary contraction. Significant correlations were found for durations of 100 ms, 30 ms, 10 ms, and 3 ms with the pudendal nerve terminal motor latency on the right and for the 3 ms and 0.3 ms durations with latency on the left. There were no correlations between the strength-duration test and resting pressure in the anal canal. CONCLUSION: The strength-duration test significantly correlates with the established measures of external anal sphincter function and its innervation. Therefore, this simple test appears to provide a simple measure of external anal sphincter denervation.